1. Field of the Invention
The present invention relates to a method and an apparatus for reviewing defects that have occurred in processes of manufacturing thin film devices such as semiconductor electronic circuit substrates and liquid crystal display substrates, by using a magnification image-pickup apparatus such as a scanning electron microscope.
2. Description of the Related Art
Manufacturing of thin film devices, such as semiconductors, liquid crystal displays, and magnetic heads for hard disks, includes a large number of processes. The number of such manufacturing processes sometimes sums to several hundreds. In a case where defects such as particles and breaks in wiring occur in thin film devices due to unsatisfactory or malfunctioned manufacturing conditions in processing apparatuses, this results in an increase of the probability at which defects occur in products, and consequently, a decrease in a yield. With this taken into consideration, it is important that an apparatus in which a problem occur be identified, and that countermeasures be taken for the purpose of maintaining and improving the yield. To this end, a particle inspection, a pattern inspection and the like are performed for every main process, and thereby it is monitored whether processing is normally performed. At this time, it is not possible to perform inspections on all the substrates to-be-processed due to restrictions on time and labor. For this reason, generally, inspections are performed on substrates to-be-processed sampled on a lot basis or on a substrate to-be-processed basis, for each series of several processes. Here, a substrate to-be-processed denotes a minimum unit being processed. In a case of a semiconductor, a substrate is one sheet of wafer.
In a case where a particle inspection is performed by using an inspection apparatus, for example, a wafer surface is scanned by a laser, and thereby a detection is made as to whether there is scattered light. Thus, information on the positions and the number of particles is obtained. In addition, in a case where a defect inspection is performed on particles and pattern defects together, an image of a circuit pattern of a wafer is captured with, for example, an optical magnification image pickup device, and information on the positions, the number and the like of defect points is obtained, by comparing images in adjacent areas in the same pattern with one another. Here, a “defect point” denotes a point, which is outputted as a point at which an abnormality is found out by an inspection by using an inspection apparatus. Hereinafter, the inclusion of particles and pattern defects are referred to as “defects.”
A determination as to a device malfunction is often made by using, as a control index, the number and the density of defects detected by an inspection apparatus. That is, it is determined that a device malfunction has occurred when the number of defects exceeds a predetermined reference value. On the basis of defect coordinate information detected by the inspection apparatus, images of the defects are magnified, and the images thus magnified are taken by using a review apparatus such as an optical microscope or a scanning electron microscope (SEM). Thus, detail information on the sizes, shapes, textures and the like of the defects is obtained by taking images of magnified defects. In addition, detail inspections, such as an elemental analysis and a cross-sectional observation and the like, are performed, and thereby it is identified which of the apparatuses is malfunctioning and which mode of defect occurs. By using these results, measures are taken for apparatuses and processes, thereby preventing a yield from decreasing.
In order to automate such review operations and make them more efficient, review apparatuses having a function (Automatic Defect Review: ADR) have been recently developed (refer to Japanese Patent Application No. 2000-30652). The ADR function causes magnified images of particles and defects to be automatically captured by using inspection data from a particle inspection apparatus and a defect inspection apparatus. Moreover, Japanese Patent Application No. Hei 7 (1995)-201946 discloses a technique in which captured images are automatically classified (Automatic Defect Classification; abbreviated as ADC) according to a specific rule.